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fix the "remove task_ppid_nr_ns" commit

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Commit 84427eaef1 (remove task_ppid_nr_ns)
moved the task_tgid_nr_ns(task->real_parent) outside of lock_task_sighand().
This is wrong, ->real_parent could be freed/reused.

Both ->parent/real_parent point to nothing after __exit_signal() because
we remove the child from ->children list, and thus the child can't be
reparented when its parent exits.

rcu_read_lock() protects ->parent/real_parent, but _only_ if we know it was
valid before we take rcu lock.

Revert this part of the patch.

Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Oleg Nesterov 2008-01-15 00:02:37 +03:00 committed by Linus Torvalds
parent 4fd3670eb1
commit a98fdcef94
1 changed files with 1 additions and 1 deletions
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2
fs/proc/array.c
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@ -426,7 +426,6 @@ static int do_task_stat(struct task_struct *task, char *buffer, int whole)
cgtime = gtime = cputime_zero;
rcu_read_lock();
ppid = task_tgid_nr_ns(task->real_parent, ns);
if (lock_task_sighand(task, &flags)) {
struct signal_struct *sig = task->signal;
@ -465,6 +464,7 @@ static int do_task_stat(struct task_struct *task, char *buffer, int whole)
}
sid = task_session_nr_ns(task, ns);
ppid = task_tgid_nr_ns(task->real_parent, ns);
pgid = task_pgrp_nr_ns(task, ns);
unlock_task_sighand(task, &flags);